John n



" rate; 22,1926. 3

UNITED- STATES PA TEN-T OFFICE.

JOHN N BURDIOK, OF BUF I ALO, NEW .YORK, ASSIGNOR '10' OARBllDE AND CARBON CHEMICALS CORPORATION, A CORPORATION OF NEW YORK.

rnocnss or Maxine PROPYLENE mm.

No'Drawing. Original application filed August 7, 1923, Serial No. 656,304. Divided and this application filed November 14, 1925. Serial No. 69,166. The invention is a process of making for the apparatus, good yields being neverpropylene oxide. In accordance withv the theless obtained. In. .other words, the invention, propylene chlorhydrin is decomstrength of the solution is as free from re-' posed by the action of strong alkalis such strictions as is generally the case in chemi- 5 as the hydroxides of the alkali and alkalinecal processes.

earth metals. 1 p A single condition must be fulfilled in This application is a division of my coorder to secure the result referred to above, pending application, Serial No. 656,304, .this being that the olefin oxide formed filed Aug. 7, 1923.. must be removed at such a rate that there The known methods of making olefin is no substantial accumulation of it in the chlorhydrins give'dilute solutions-very difsolution. p ficult to concentrate, since the chlorhydrins The invention is not restricted to any parform azeotropic mixtures with water. The tieular method of removing the olefin oxide reaction whereby the chlorhydrins are 'deas formed. Heating the solution in which 5 composed with strong alkalis to give olefin the reaction takes place to or near its boiloxides has been known for over half acening pointunder atmospheric or reduced tury, but it has hitherto been regarded as pressure, is usually the'simplest, and is preimpossible to obtain acceptable yields of the fer-red; but other expedients giving like reoxides by this method unless very strong sults may be used. Appropriate methods solutions of chlorhydrin were used. Thus, should be used to separate the evolved oxide a recent U. S. patent, Brooks 1,446,872, from any steam or other gas with which it 75 dated Feb. 27, 1923, contains the following may come off. statement on this point: In a preferred form of the invention the If this reaction between a chlorhydrin chlorhydrin solution, a 10% solution of and a caustic alkali is carried out in the propylene chlorhydrin, is placed in a kettle presence of considerable water, very poor provided with a rectifying column suryields of oxide result, as described in the mounted by a reflux condenser. The chlorchemical literature. Glycols and condensahydrin solution is heated to boiling and a tion products of unknown structure are the solution of caustic soda added continuously chief products resulting under these condiat such a rate as to bring about a suitable tions, as for example with a 20 per cent evolution of propylene oxide. The oxide to- 85 solution of ethylene chlorhydrin and a 20 gether with steam passes into the rectifyper cent solution of caustic soda a yield of ing column where the steam is mostly conethylene oxide equivalent to about 12 per densed and returned to the kettle. The cent of the theory is obtained. If substanropylene oxide, ha.ving a much lower boiltially anhydrous chlorhydrins are subjected mg point than water, passes through the 90 to the action'of solid-and substantially dry reflux condenser as vapor and is liquefied" caustic alkali (this expression of course inin a separate condenser cooled to a lower eluding lime), excellentyields of the oxides temperature, for example with cold brine. 40 may be obtained. A yield of more than 90% will be obtained. 'Accordingly, so far as I am aware, all he kettle referredto should be heated to 95 workers in this field have resorted to the such a temperature that the oxide is evolved A difficult 'concentrationof the chlorhydrin practically as. fast as formed without an solution before applying the oxide-forming undue amount of steam passingofi with it. reaction. The caustic solution may be of any con- Contrary to this universal belief, I have venient strength, but since stro caustic 1 found that dilute solutions of chlorhydrins solutions are usually as cheap, .re erred to will give high yields of olefin oxides when the contained alkali, as dilute solutions, and treated with strong-alkalis. Solutionscon .since strong solutions permit the-use of taining 10% or less of chlorhydrin will smaller apparatus, they are preferred. t give or more of the theoretical yield 'Subject to the other conditions noted, 1 5 of olefin oxide. The quantity of water is many" modifications are possible. Alkalis' immaterial and the solutions may be as diother than caustic soda, and other methods lute as is consistent with a reasonable size of mixingthe reacting-materials, may 0 siblejto obtain good yields with solutions containing less than 40% chlorhy'drin, and

preferred still more highly concentrated solutions,

I regard the use of all solutions having propylene chlorhydrin concentrations'of less than about 40%, under such conditions as to give acceptable yields of olefin oxides, as a new field, and I regard this entire field as the scope of my invention. 4

As used in. the appended claims, dilute chlorhydrin solution imports a chlorhydrin solution of less than about 40% chlorhydrin content. Solutions containing less than about 15% chlorhydrin are most readily obtainable, and the use of solutions within this range of concentration is a preferred application of my invention.

I claim 1. Process of making propylene oxide which comprises reacting. upon a dilute 'sochlorhydrin solution higher than about 15% with a strong alkali formed.

of a concentration not and removing the propylene oxide as 3; Process of .making propylene oxide which comprises reacting upon 'a dilute solution of propylene chlorhydrin with a strong alkali, and removing the'propylene oxide as formed by heating the reaction liquid.

4. Proeess'of making propylene oxide which comprises reacting upon a propylene chlorhydrin solution of a concentration not higher than about 15% with a strong alkali and removing the propylene oxide as formed by heating the reactioniliquid. I

5. Process of making propylene oxide 45 which comprises adding -a solution of a caustic alkali to a'dilute solution of propylene chlorhydrin while maintaining the chlorhydrin solutionat .such temperature that .the propylene oxide. is evolved. as formed, and separating the propylene oxide so producedfrom the accompanying water vapor.

In testimony whereof I affix my signature.

JOHN N. BURDICK. 

